AUSTIN (AP) – Officials are set to again brief members of a key Texas House committee on their ongoing investigation into the fertilizer plant explosion that killed 15 people in the town of West.

Members of the lower chamber’s Homeland Security and Public Safety Committee will hear from investigators on Monday.

Their only other briefing came early last month on the April 17 blast that also injured about 200 people in the rural farming community. Since then, investigators have said the cause of the fire that sparked the explosion remains unknown and may never be determined.

Still, the committee is examining whether proper regulations were followed, and if the plant received enough official oversight prior to the blast.